textproduct: Quad Cities

KEY MESSAGES

- A passing system will bring the risk of thunderstorms to the area on Wednesday. The SPC has parts of the area under a Marginal (level 1 out of 5) Risk of severe storms during the afternoon. If severe storms occur, the primary risks would be hail and damaging winds.

- A pattern change this weekend and into next week will bring high humidity and above normal temperatures to the area. Heat headlines may be needed at times next week.

SHORT TERM /THROUGH WEDNESDAY/

Issued at 208 PM CDT Tue Jun 23 2026

Satellite shows building cumulus either side of a line from Manchester, IA to Woodhull, IL. It is only a matter of time before showers and a few thunderstorms develop within this band. Once convection develops, it will continue through sunset and then dissipate. Overall coverage looks to be 15-30 percent.

Late tonight and into Wednesday morning a band of WAA precipitation will move into the area in the form of nocturnal convection. Overall coverage will range from 20-40 percent with the nocturnal convection slowly dissipating Wednesday morning as the LLJ weakens.

Wednesday afternoon the cold front moves into the area. The combination of the front, leftover boundaries from the earlier convection and differential heating will allow diurnal convection to develop during the afternoon.

Colder air aloft arriving with the associated upper level disturbance will steepen mid-level lapse rates and increase the potential for the stronger storms to produce hail.

The stronger mid-level winds aloft remain across Wisconsin, but, the progged steep lapse rates across the area does raise the possibility of locally damaging winds in the form of downbursts.

LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/

Issued at 208 PM CDT Tue Jun 23 2026

Wednesday night through Saturday night Assessment...high (>80%) confidence of humidity levels remaining fairly comfortable. Medium (35-50%) confidence on rain chances

Convection that develops Wednesday afternoon will continue into Wednesday evening and dissipate with sunset.

A storm system is forecast to pass through Missouri and into the Ohio Valley Thursday afternoon into Friday evening. Areas generally north of Highway 30 look to remain dry through the end of the week. Areas south of I-80 run the risk of seeing some rain (current chances are 20-30%). However, the better rain chances generally look to be south of an Ottumwa, IA to Galesburg, IL line.

If the system would shift further south (probably of this occurring is 30-40% due to the dry easterly flow), then much of the area would remain dry the remainder of the week.

Sunday through Tuesday Assessment...very high (>90%) confidence of increasingly hot and humid conditions

By Sunday the pattern change to an upper level high over the Ohio Valley will be in place and strengthening. Said large scale pattern will generate moderately strong southerly flow that will bring increasingly humid conditions to the area along with above normal temperatures.

Sunday through Monday will be dry as the main storm track is well north of the area. How high the dew points get are still somewhat in question but readings of 70 to 75 are very likely to occur especially given the recent rainfall across the area.

Going on the basis of 70 to 75 dew points, heat indices Sunday would be in the mid to upper 90s across the area with readings over 100 on Monday.

Thus the potential is there for heat headlines on Monday. The current probability looks to be 33-40% right now.

Monday night into Tuesday the heat and humidity will continue. However, a system in the Plains raises questions regarding the position of the main storm track. Does it remain well north of the area or does it shift southward due to the Plains system?

From the large scale picture, there are dual upper highs; one in the Ohio Valley and the other near the Gulf Coast. Some solutions retrograde the Ohio Valley upper high westward. If this is correct, then the storm track for organized storm complexes would remain well to the north of the area. Some other solutions allow the Ohio Valley high to move toward the east coast, which would allow the main storm track to move south.

If the main storm track would move south, heat and humidity would continue past Tuesday but would be interspersed with thunderstorms. Right now the model consensus is suggesting the storm track to move south and grab parts of the area. With PWATS forecast to be 1.5 inches or higher, this scenario would also bring the risk of heavy rainfall with reach round of storms.

AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/

Issued at 1213 PM CDT Tue Jun 23 2026

Isolated diurnal convection will develop across eastern Iowa through 01z/24. The probability of a TAF site being impacted is around 20 percent. After sunset winds will be under 10 knots. After 12z/24 decaying nocturnal convection may move into the Highway 20 corridor.

DVN WATCHES/WARNINGS/ADVISORIES

IA...None. IL...None. MO...None.